Production of butadiene



Patented Jan. 2 4, 1939 UNITED STATES PATENT OFFICE" 2.145.059 PRODUCTION or BUTADIENE Robert Stadler, Heidelberg, Karl Ackermann,

Mannheim, on-the-Rhine anljtnfln Lehrer Ludwigshafenassignors to I. G. Far- Germany benindus'trie Aktiengesellschaft, Frankfort-onthe-Main,

No Drawing. Application April 2c, 1938, Serial No. 204,460. In Germany May 3, 193'! The present invention relates to a process of producing butadiene from vinylacetylene.

We have found that butadiene can be obtained in asimple and especially economicalmanner by 5 treating vinylacetylene with 'amalgams of alkali metals in the presence of substances which de: velop hydrogen with the said amalgams. This is surprising because under the same conditions it is practically impossible to convert acetylene carried out by bringing theamalgam together with water in a stirring vessel and leadingin gaseous vinylacetylene. Gaseous vinylacetylene may also be led together with water vapor through or over anhydrous amalgam at'elevated temperature. By varying the amount of water vapor, the amount ofl vdrogen evolved and con.-

sequently the speed of the reaction may be influenced in any desired manner, Furthermore, liquid amalgam and a liquid which contains vinylacetylene dissolved therein and develops hydrogen with amalgams, as for example an alcohol, may

be caused to react on each other in countercurrent.

The activity of the amalgams of the individual alkali metals is different. Sodium amalgam aels most slowly, p tassium amalgam acts appreciably more rapidly and rubidium amalgam has especially great hydrogenating action. Contrary to expectation, the action may be increased by using mixed alkali amalgams, as for example sodium- 4 potassium amalgam. Such amalgams may also be more highly laden with alkali metal than the simple alkali amalgams without becoming solid.

The action of the amalgams may also beinfluenced by the addition of other metals. An addition of thallium has an especially accelerating action. By adding electrolytes, such as potassium phosphate, common salt, zincsalts or chromium salts to the reaction liquids or by adding certain gases to the vinylacetylene, the

0 reaction may also be influenced. 'Ihusthe addi-. tion of 10 per cent of carbon dioxide to gaseous vinylacetylene increases the speed of hydrogenation to more than twice. During the reaction the alkali amalgam decomposes, for example under the action of water, in o my.

hydrogen and alkali solution which remains practically pure and may therefore profitably be employed. The mercury separated may be alloyed with fresh alkali metal.- The amalgam obtainable by the electrolysis of alkali may also be 5 directly used.

The following examples will further illustrate how this invention maybe carried out in prac-- tice but the invention is not restricted to these examples. The parts are by weight. 10

I Example 1 9 liters of vinylacetylene which are led in a cycle are treated in a stirring vessel with 1500 grams of 2 per cent potassium amalgam and 16 waterat ordinary temperature. After an hour a sample of the gas has a content of 10.7 per cent of butadiene. After treatment for a further hour at 55 0., the gas has the following coinpositlom- 20 Per cent vinylacetylene. 32.6 Butadiene- 56.6 Omem 0.4 Hydroge 8.7 25 Methane and homologues 0.0 Nitrogen 1.7

The gas is then liquefied and fractionally distilled. At from 4 to 3 below zero C., practically pure butadiene is obtained which may be poly- 9 merized to rubber in known manner.

Example 2 1300 grams of rubidium amalgam with about 1.5 per cent f rubidium are shaken with 400 cubic 35 centimeters of waterand' 2.5 liters of gaseous vinylacetylene for 5 minutes at 20 C. vigorously Example 3 In an elect rolyzing vesselwith 5.5 kilograms of mercury containing 10 per cent of thallium, 20 per centcaustic potash solution is continuously electrolyzed. The amalgam thus formed is 50 led in a cycle through a vessel in which it is brought into intimate contact with water and vinylacetylene, then pumped back again to the vessel. The caustic soda solution electrolyzing I tanned is replaced by fresh water continuously or periodically. By a single e 0118 liters per hour of vinylacetylene there are obtained about 42 vper centoi 1.3-butadiene and about 8 per cent of 1.2-butadiene or methylallene besides less than 2 per cent of free hydrogen. No paraiiln hydrocarbons can be detected in the gas.

In the same manner there can also be employed vinylacetylene containing about 4-5 per cent of acetaldehyde and some per cent of di-. acetylene, such as is obtained by treating electric arcacetylene containing about' 90 per cent of acetylene and about 4 per. cent oi; diacetylene witha solution of cuprous chloride and ammonium chloride in known manner; If about 40 per cent of thesa'id vinylacetyleneareconverted into butadiene, the diacetylene present I has been reduced. The acetaldehyde-contained in the vinylacetylene does not cause anytrouble. It is converted'into ethyl alcohol by the amalgam employed Example 4 1 liter of gaseous vinylacetylene is vigorously.

shaken with a mixture 01' 300 grams 01' ,2 per cent sodium amalgam or 500 grams of 2 per cent potassium amalgam and 300 cubic centimeters of an aqueous solution of 50 vgrams zinc chloride (anhydrousi and 1 gram of butyl naphthalene sulphonic acid sodium salt,'which solu-- tion may further contain, it desired,'60 grams 0! sodium hydroxide. I Butadiene being practicalhydrogen.

ly 'i'ree from butylene is thus obtained besides unchanged vinylacetylene and small amounts of What we claim is:

1. A} process oi producing butadiene which comprises treating vinylacetylene with amalgams 'of alkali metals in the presence 01' substances which develop hydrogen with the said amalgams. 2. A, process of producing butadiene which comprises treating vinylacetylene with amalgamof alkali metals in the presence of a substance 1 amalgams of alkali metals in the presence of substanceswhich develop hydrogen with' the said 'amalga'ms. '6. A process of producing butadiene which comprises treating vinylacetylenewith amalgams of alkali metals and of thallium in the presence of substances which develop hydrogen with the said amalgams.

ROBERT STADLER.-

KARL ACKERMANN. 

